Final answer:
piRISC functions to silence transposable elements by inhibiting their transcription and causing degradation of their RNA, so the answer is Both a and b.
Step-by-step explanation:
The function of piRNA-induced silencing complex (piRISC) in relation to transposable elements (TEs) is to ensure that these elements do not disrupt normal cellular functions. piRISC is involved in the silencing of transposable elements primarily by two mechanisms:
- Inhibiting transcription of transposable elements (TEs).
- Causing the degradation of TE RNA.
Therefore, the correct answer would be Both a and b: piRISC inhibits transcription of TEs and causes the degradation of TE RNA.