The correct option is
A S P R Q
The sentence is in reported speech. In reported speech, there will be a reporting verb and a main verb. The reporting verb comes first. The reporting verb "claimed" is in the option "S." Hence, "S" is the first option in the sequence.
Next comes the speech that is being reported. It's basically a sentence. Every sentence starts with a subject. Out of P, Q and R, only P has the subject, i.e., "She." Although "his phone number" can be used as both a subject and an object, the word "She" can act only as a subject as it is a subject pronoun and hence, cannot be used as an object. So, the subject here is "She." Thus, P is the second option.
Subjects are followed by verbs. In this case, the reported verb is "didn't know," which should follow the subject "she." So, the third option in the sequence is "R."
"His phone number" can only act as an object, as discussed earlier. This object follows the reported verb, which in this case, is "didn't know." Thus, the final option in the sequence is "Q."
The correct sequence is SPRQ and the sentence is "She claimed she didn't know his number."