Read the following passage and answer the questions.

"In the early 1980s, Paul Romer challenged the conventional view among economists that productivity growth was exogenous, meaning it could not be influenced by anything else in the economy. He introduced endogenous growth theory, which posits that technological change is the result of efforts by researchers and entrepreneurs who respond to economic incentives. This technological change is the prime mover of the nation. Romer emphasized that factors such as tax policy, basic research funding and education could potentially influence long-term economic prospects.

Romer's 1990 paper marked a turning point in the understanding of economic growth. He highlighted". The significance of ideas in driving growth and emphasized that ideas are non-rival goods, unlike standard goods in classical economics. This nonrivalry of ideas leads to increasing return to scale, as the same idea can be used repeatedly without being depleted. Romer argued that growth in income per person is tied to growth in the total stock of ideas, rather than growth in ideas per person.

Further more, Romer's work suggested that in a perfectly competitive equilibrium with no externalities, the optimal allocation of resources cannot be decentralised. Instead, imperfect competition and externalities to the discovery of new ideas are likely to play important roles in driving innovation and growth.