Reproduction of ϕ ×174, a single-stranded DNA phage involves several steps. A few statements are given below to explain the mechanism.
A. The single-stranded ϕ ×174 DNA is converted into a double-stranded replicative form (RF)
B. Replication of double-stranded replicative form results in the production of single-stranded phages, about 50% of which are +ve sense phages and the remaining are -ve sense phages
C. Replication of the double-stranded replicative form results in the production of only -ve sense phages
D. Replication of the double-stranded replicative form results in the production of only +ve sense phages

Choose the option that correctly describes the process.

Correct option is D

Explanation-

φ×174 (phi X 174) is a bacteriophage (virus that infects bacteria), and it contains single-stranded (+) sense DNA. Its replication involves a replicative form (RF), which is a double-stranded DNA intermediate used for replication.

Statement A -  "The single stranded φ×174 DNA is converted into a double-stranded replicative form (RF)"  - CORRECT
When φ×174 infects E. coli, the single-stranded (+) DNA is first converted into a double-stranded replicative form (RF) by synthesizing the complementary (-) strand. This RF is used as a template for further replication and transcription.
Statement B -  "Replication of double stranded replicative form results in the production of single stranded phages, about 50% of which are +ve sense phages and the remaining are –ve sense phages"  - INCORRECT
Only +ve sense single-stranded DNA is packaged into progeny phages. The phage only produces + sense ssDNA, which is then encapsidated (enclosed in the protein coat). The (-) sense strand is not packaged; it's only a template.
Statement C -  "Replication of the double stranded replicative form results in the production of only –ve sense phages"  - INCORRECT
As stated above, only +ve sense strands are produced for packaging.
Statement D -  "Replication of the double stranded replicative form results in the production of only +ve sense phages"  - CORRECT
From the RF, multiple +ve sense ssDNA molecules are synthesized and packaged into new phage particles.

Final Answer -
Correct option :   d (A and D).