Its basic strength is `10^(10)` more than 1-dimethyl amino naphthalene. Reason for high basic strength is :

Options

A. resonance
B. steric inhibition of resonance
C. ortho effect
D. hyperconjugation

Explanation

Steric effects can indirectly affect acidity or basicity by affecting the resonance:
Steric effects can also be caused by other types of strain. 1,8-bis(diethylamino)-2, 7-dimethoxynaphthalene (1) is an extremely strong base for a tertiary amine (`PK_a` of the conjugate acid=16.3, compare N,N-dimethylaniline , `pK_a` = 5.1), but proton transfers to and from the nitrogen are exceptionaly slow , enough to be followed by a uv-spectrophotometer. 1 is severely strained because the two nitrogen lone pairs are forced to be near each other. Protonation relieves the strain: one lone pair is now connected to a hydrogen, which forms a hydrogen bond to the other lone pair (shown in 2). The same effects are found in 4, 5-bis (dimethylamino) fluorene (3) and 4, 5-bis(dimethylamino).