Final answer:
The incorrect pair is option d. Notch1 is actually active during early T-cell development for differentiation of precursor cells into T cells, not turned off until single positive. The other statements are correctly matched with their expression patterns.
Step-by-step explanation:
The question is asking us to identify which pair concerning T-cell surface molecules and their expression patterns is incorrectly matched.
The matching that is incorrect is option d. Notch1 does not remain turned off until the thymocyte becomes single positive. Notch1 is crucial for T-cell lineage commitment and is active during the early stages of T-cell development in the thymus. It is involved in the differentiation of precursor cells into T cells, rather than being active only at the later single-positive stage.
The other options describe correctly the expression patterns of T cell-related proteins. Early in T-cell development, pTα (option a) and TdT (option b) are indeed turned on and then turned off after the T-cell receptor (TCR) is established or the α-chain is rearranged, respectively. CD3 (option c) is expressed throughout T-cell development as part of the TCR complex. RAG genes (option e) are turned on early in development to mediate V(D)J recombination, turned off once the TCR is successfully rearranged, and can be turned back on in certain conditions such as receptor editing.