The correct option is C ALU element
The most abundant mobile elements in mammals are moderately repeated DNA sequences, which form two classes- (i) LINES or Long interspersed elements and (ii) SINES or short interspersed elements. SINES constitute some 13 percent of human genome. Most abundant SINES are Alu elements, so named because most of them contain a single recognition site for the restriction enzyme ALU 1. ALU elements are scattered throughout the human genome at sites where, their insertion has not disrupted gene expression like between genes within introns etc.
So, the correct answer is option A.