If a, b, c are positive and are the pᵗʰ, qᵗʰ, rᵗʰ, terms respectively of a G.P., show without expanding that
Δ = log a p 1
log b q 1
log q r 1 is

A. 0
B. log (abc)
C. -(p + q + r)
D. none of these