The treatment of $$C{H_3}MgX\,\,$$ with $$C{H_3}C \equiv C - H$$ produces

The absolute configuration of

The electrophile, $${E^ \oplus }$$ attacks the benzene ring to generate the intermediate $$\sigma - $$complex. Of the following, which $$\sigma - $$complex is lowest energy?

$$\alpha$$-D-(+)-glucose and $$\beta$$-D-(+)-glucose are