Select the option that expresses the given sentence in indirect speech.
Riya said to me, “I am happy to see you.”

Correct option is A

“Riya told me that she was happy to see me.” is correct indirect Speech.
Direct speech- Direct speech, also known as quoted speech or direct quotation, is a way of reporting someone's exact words.
Indirect speech- Indirect speech, also known as reported speech or indirect quotation, is a way of reporting someone's words or thoughts indirectly, without using their exact words.
Rules for converting direct speech to indirect speech-
· When the reporting verb of direct speech is in past tense then all the present tenses are changed to the corresponding past tense in indirect speech. 
· Reporting verbs such as ‘said/ said to’ changes to said, told.
· Comma inverted comma will be replaced with conjunction “That”.
· The  first person in direct speech  changes as per the subject of the speech.
· The  second person of direct speech  changes as per the object of reporting speech.
· The  third person of direct speech  doesn’t change.
When converting from direct to indirect speech, the present tense "am" changes to the past tense "was," reflecting the shift in the reporting time frame.